24 March 2017

One Line to Rule the World

Spring has arrived, and with it, daylight saving time. As the clocks go forward an hour in the UK, as they did earlier this month in the US, we’re taking a look at how Greenwich became the home of time. A new book by Geographer Royal for Scotland, Professor Charles Withers, asks the question, how did the prime meridian, a singular world-ruling feature, come to be sited in southeast London? Why was it chosen over Washington, Paris, or Beijing? The passage below, excerpted from the prologue ofZero Degrees: Geographies of the Prime Meridian, explains how the choice of Greenwich to mark 0° longitude would go on to solve complex problems of global measurement that had engaged geographers, astronomers, and mariners since ancient times.

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In November 1883, a sixty-seven-year-old English sailor addressed a letter to the world’s geographical societies. There are, he began, “some things that belong to all mankind.” What William Parker Snow had in mind was nothing less than a single prime meridian, a global base point or line to be used by all nations. From such an agreed point of terrestrial measurement, he reasoned, navigators and geographers could plot their voyages and align their maps, and perhaps astronomers could even chart the heavens, all using a standard point of earthly reference. One prime meridian for the world and only one, stressed Parker Snow, would be of “vast benefit to Science and Humanity.”

His appeal for a uniform base of measurement was rooted in personal experience. Born in 1817 in Poole, England, William Parker Snow was a sailor, an author, a sometime Patagonian colonist, a historian of the American Civil War, and, important to his own self-image, a veteran of Arctic exploration. He was also reputed to be psychic and lived, as one contemporary remarked, “on the edge of the Fourth Dimension.” Parker Snow’s supposed otherworldly powers, revealed in a dream in January 1850, convinced him (but few others) of the location of the ill-fated Franklin expedition that was lost in the Arctic in 1847–1848. As a young man, Parker Snow had himself nearly perished at sea during a storm when his vessel had a close encounter with another ship that had derived its mid-ocean position and course from an initial meridian different from his own.

Parker Snow’s entreaty was timely. In the late nineteenth century, there was no such thing as a single prime meridian. There was no shared global 0° base point from which the world’s dimensions were reckoned in common—no one site of calculative origin from which geographers, navigators, astronomers, and timekeepers could fix their respective systems of measurement. Nor had there ever been. By the 1880s moves were certainly being made in several quarters to adopt a single prime meridian for the world. Parker Snow was aware of them. Yet during his time, the story of the prime meridian—its history, its geography, and its use by different nations and communities—was one of persistent national difference. The entry “meridian” in the 1825 London Encyclopedia, for example, makes the nature of the problem clear: “The first meridian of a country is that from which its geographers, navigators, and astronomers, commence their reckoning of Longitude; and, the meridians having nothing in themselves to distinguish them from each other, the fixing upon any one for this purpose is quite arbitrary; hence different persons, nations, and ages, have commenced their longitudes at different points, which has introduced no small confusion into geography.” For that author, at least, there was no likelihood that these differences and the resultant confusion would ever be reconciled: “National and even scientific jealousies are too strongly prevalent for us to hope that the world will at any early period fix on a common first meridian.”

Parker Snow lived in a world where more than twenty prime meridians were at work. Several European nations had long used the island of Ferro, the westernmost of the Canaries, as a prime meridian. This choice of geographical origin was an intellectual inheritance from the ancient Greeks. By 1825 and for some time before, however, as the London Encyclopedia further reported, individual nations had commonly employed their own initial meridian: “Each considerable country now usually adopts the meridian of its own capital as the first.” France, for example, used two— Ferro and from about 1720, Paris, centered upon the observatory there. After 1776 the United States did as well, employing Washington, DC, for astronomical purposes and Greenwich, England, for geography and navigation: this twin primacy was enshrined in U.S. law in 1850. In Britain from the later 1760s, the prime meridian most commonly used for navigational purposes was that based upon the Royal Observatory at Greenwich.

The idea behind the creation of a single prime meridian was to solve the geographical confusion caused by lasting and different national practices. Having one first meridian could save lives, standardize maps, unite various scientific communities, and provide a base point from which to regulate the world’s measurement in space and in time. It would not, however, be easily achieved. To create a single prime meridian for the world required nothing less than undoing centuries of established national practice.

Within a year of William Parker Snow’s letter, though certainly not in direct answer to it, geographers, astronomers, navigators, and politicians from over twenty countries met in Washington, DC, at the International Meridian Conference in order to propose a single prime meridian for the good of the world. Of Parker Snow there is no sign. No trace of his proposal exists in the concerns voiced in the meeting. Yet in Washington one prime meridian was proposed above all others as the world’s originating point of measurement for use in mapping, navigation, astronomy, and timekeeping. This was determined not by what nature provided, as Parker Snow had hoped, but through political and scientific debate over where and why and how one prime meridian among many should serve as the world’s 0°.

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